Process for producing dextran derivatives and products resulting therefrom



July 1962 P. e. M. FLODIN ETAL 3,042,667

PROCESS FOR PRODUCING DEXTRAN DERIVATIVES AND PRODUCTS RESULTING THEREFROM Filed March 10, 1959 INV T0 Per Gusmf Mognus l odirf Bjor Gustaf-Adolph lngelmon PM Attorneys United States Patent-Gil" 3,042,667 Patented July 3, 1962 3,042 667 PRoenss For: Pnonucn so DEXTRAN nnrnvA- gr gns AND PRQDUCTS RESULTING R M Per Gustaf Magnus Flodin and Bjorn Gustaf-Adolflngelman, .Uppsaia,. Sweden, assignors. to Aktiehoiaget Pharmacia, Uppsala, Sweden, 21 company of Sweden Filed Mar. 10, 1959, er. No. 798,541 8 Claims. (Cl. 260209)- THE INVESTMENT BROADLY The process according to'this invention generally involves reacting a hydroxyl group containing dextran sub- This inventio'nalso encompasses stance in aqueous solution in the presence of an alkaline reacting catalyst with a..bifunctional organic substance capable of reacting With the hydroxyl groups of the dextran substance which results in the formation of a copolymerizate in the form of a gel 'containing the molecu-les of the dextran substance bound together byether bridges of the type R OX-OR+ wherein-R= represents the molecules of thedextran substance and X is an aliphatic radical obtained from thebifu'nctional substance containing from about?) to 10 carbon atoms:

THE IHYDROXY'L GROUP CONTAINING DEXTRAN'SUBfiTANCE The term dextran substances as used in the present specification and in theappende'cl'claims is' intended to encom'passpolymers of'dextran having an average mole-- cular Weight ranging from 1000 up to-several millions,-or I even hundreds of millions and consisting of glu'coseresidues bonded together -by-mainly alphal ,6-glycoside e linkages.-- Thus, for example; suitable 'dextran substances 3 for the reaction of the presentinvention WOIIIddHClUdB native dextran or partially depolymerized dextran obtained byhydrolysis of native dextran, or .hydrophilic hydroxyl group-containing derivatives of 'dextran, .011.

neutral hydroxyl grpuprcontaining hydrophilic. derive tives of dextran orpartiallydepolyrnerized dextran, such I. as ethyl, hydroxyethyl or l-hydroxypropyljethers. off. dextran, or' dextran glycerine glucoside, or hydrodextran V (ile. dextran; the reducing endzgroups of Whichghave been reduced to alcohol groups), or hydroxyl groupc011 taining hydrophilic derivatives of dext'ran or partially depolymerized dextran containing acid or basic groups, for example, carboxyl. groups, sulphonic acid: groups;:- or amino groups or substituted amino groups} such as car are oxidized to carboxyl groups.

boxymethyldextran or dextran, the end groups oewhien Often fractions oftheabove-mentioned dextran substances may also advantage,

ously be used;

THE BIFUNCTIONAL ORGANIC SUBSTANCE Suitable bifunctional substanceswfor carrying out the process of this invention may be selected from bifunctional glycerinederivativessuch as epiehlorohydrimdichlorohydrin, 1,2,3,4-diepoxybutane, bis-'epoxypropyl-ether, eth ylene glycol-bis-epoxypropyl(ether and- 1,4-butanediol bi's-- epoxypropyl ether and closely related compounds;

THE. AQUEOUS MEDIUM REACTION T CATALYST.

The reaction is carriedoutin'aqueous solutionrand in}, the; presence of analkaline. reacting; substance having as, catalyzing efiect on the reaction.;-. Examples of suitable catalysts are the alkali metal hydroxides, preferably 50- I dium hydroxide, and the alkaline earth metal hydroxides, and also tertiary and quaternary amines. H halogen hydrines are used .as bifunctional' organic substances, the alkali or alkaline compound should preferably also 'SfiIVG; to neutralize the hydrogen halide split off in the reaction, aud tor this purpose the amount of the alkaline compound should be greater thanthatwhich would other-. Wise be required for the reaction $013.8 tozmaintain-za pI-Iv above 7 in the: reactiommix'ture;

REACTION" TEMPERATURES 'ANDTTMES v The reaction temperature maybe varied wide limits and 'asa consequence the-reaction-time'will be dependent to a certain extent onqthe, reaction tempera-1 ture which has been chosen. With regard to. the-speed of reaction it is advisable tor-not workat toolowva tem-.; perature.- Howeven-on the; other, hand, in order to avoid undesirable side reactions, the temperature should notbea too high, and in certain instancesitlmay be desirable to.l utilize coolinggmeans'toncontrol thehtemperature of the reaction. With due consideration to these circumstances,; itis preferred to carry out the reaction at a temperaturebetween about 15 C. and 6090 C., preferablywithin the range of 30-70";- C.. However,.it is conceivable that .higher or lower temperatures could the used v uu'dercertain oircumstafices- Depending onthe. reaction temperature, ,ftherv reaction medium, the reaction temperature etc:, thei formation;

of a gelacopolymerizate:usuallytakes place in a matter 7 of hours, forexample, from about 2 to 4 hours orhin SOIHB instances even SO0E61.

TTI-IE AMOUNTS OF THE REACTANTS 'AND THE=- 'MIXING'THEREOF The concentration of :the dextran substance in said aqueous solution may suitably bewithi'n theflrangepofi The reaction is preferably carried vout by ,all of thereactatits, together; at once, butitis-f alsopossible ,tol carry, out thesreactionin'. steps, forwexample, in such 21a Way that,theldextrangsubstance ,is causedto reaotyvithi, amounts of the, hifunctio'nal substance which. are added successivelystepwise, whereby thgaverage molecular Weight ,ofthe productis'increased inllstepsl manner 1 p of working maybe suitable, Whnit isdesired to subject theproduct to an intermediate purifying treatment-before gelformat-ionn, j' j will,

.CURINGANDsTREAIINGlIHBxGELz,

The aforesaid gel copolymerizateispreferably subjected to a curing step and although the curing-conditions-are'i not critical, they are preferably carried: out at -an elevated temperatureWithin-therangeof about 303- C: and-fora time generally within the range 05 540-48 hoursg to' j complete the reaction. After. curing, the gel copolymerizates obtained in the reaction are preferably ground to a suitable particle size; neutralizedandasubjectedtoa purification by washing) The-particle; size should besuch that the purification is notrendered difiie'ult due to the factthat the diffusion equilibriumis reached too slowly? For this purpose it has 1 been-found suitable togrind-the a cal from the bifunctional substance.

glycerine derivative is used, for example epichlorohydrin,

wherethe radical X contains? carbon atoms.

technical preparations.

gels to an average particle diameter within the range of about 0.01 to 2.0 millimeters. The purification may then purities'mechanically, whereas when the gel swellsunder the influence of water, these impurities can pass out of the gel particles by difiusion;

,CHEMICAL rnornn'nns on THE REACTION PRODUCT 1 As indicated above, the copolymerizationgel product obtainedaduring thereaction contains the molecules of the dextr'an substance bound together by ether bridges ;which are of, the common type -RO-XO.R,

wherein R represents the radicals or residues of the moiemiles of the dextran substance and X is the aliphatic radithe bridge will be the type v w- -R:- crr .c onmn o -R The gels obtained in this way'consist of three dimensional networks of macroscopic dimensions of the mole,-

cules of thedextran substance, built up of chains of mainly alpha l,6-glucosidically bonded glucose residues, bonded together by ether bridges of the above-mentioned general type R O--XOR-, whereinR represents the dextran substances and X is the aliphatic radical in the ether bridge, said aliphatic radical X containing from 3 to carbon atoms, l V

'The structure of such a three dimensional copolym'erizate is illustrated in the drawing which shows three chains of dextran substances bonded together by three If a bifunctional speaeer istics and the basic concept of the invention. The parts and percentages are byweight, the temperature is room temperature,'-and the pressureis atmospheric, unless'othen ether bridges produced from epichlorohydrin, the radical X in said ether bridges containing 3 carbon atoms.

The said gel products are insoluble in water but capable of swelling therein due to the presence :of hydroxyl groups. The capacity of swelling of the gel product so obtained may be expressed by the amount of water in grams which'can be absorbed byfll g. of the dry gel, which is-also' known as the Water regain. The water regain for the products produced according to the invention may I be from about 1 to 50 g./ g. of the dry gel product, but

' is generallywithin the range of about .1 to g./ g. of,

dry gel product. I V I J I USES OF THE REACTION PRODUCT 7 Aside from its obvious use as a desiccant, the gel poly- V 100 g. of epichlorohydrin were added thereto.

wise indicated. The aqueous solution of sodium hydroxide is one normal, unless otherwise indicated. The molecular weight (M are average molecular weights, unless otherwise specified.

Example I 500 g. of dextran having an average molecular weight of 40,000 were dissolved in 1170 ml. of anaqueous solution of sodium hydroxide and 100 g. of epichlorohydrin were then added thereto. After the reaction had proceeded for about 2 hours at C. a gel had been formed which was cured by heating to 45 C, for an additional 24 hours. The product was ground to a particle size'ranging between about 5 0 and 200 mesh and was then neutralized with hydrochloric acid, washed on a filter with water until salt-free and then dried to constant weight in an oven at about 80 C. 560 gJof a product with a water regain of 5 g./ g. dry product were'obtained.

500 g. of' dextran (M 40,000) were dissolved in 2000 ml. of an aqueous solution of sodium hydroxide and After 4 hours at 45 C. a gel had been formed which Was cured by heating to 45 C. for 24 hours. After grinding, neutralizing, washing and drying, substantially as in Example 1, 360 g. of a product with a water regain of 13 g./ g. of the dry product were obtained.

Example 3 500. nrdeXtraH M 40,000 weredissolved in 2000 ml..of an'aqueous solution of sodium hydroxide and 185 g. of e'pichlorohydrin were then added thereto. After 2 hours at 45 C. a gel had been formed which was cured by heating to 45 C. for 24 hours. After grinding, neutralization," washing and drying, substantially as in Example l, 574 g. of a product having a water. regain of 7 g./ g. .of the dry product were obtained. 7

. Example4 Q 5 00 got dextran (M' l,800,000) were dissolved in I 2000 m1. of an aqueous solution of sodiumhydroxide and 100 g. of epichlo'rohydrin were thenadded thereto, After 1 hour at 45 C. a gel had been formed which was cured by heating to 45 for 24 hours. After grinding, neutraliof substances of different molecular dimensions by the so-' i called molecular sieving techniques, for which purpose they maybe used in'grain sizeshaving an average diam-1 eter, within the rau'geof about. 0.0l-2.0 mm. As'an ex ample of thisuseof the gels may. be mentioned the sepa- 'ration of, solutes "of colloids-from 'solutes of crystalloids :from a solution. The gels may alsobe usedas base substances'for the manufacture ofi'on exchangers. 'Fu1ther, whenthey .containacidor basic groups, for example car-- 1 boxyl groups,;sulphonic acid' groups or amino groups, they may directly be: used as. ion exchangers with valuable properties; Other purposes of utilization areas disintegrating agents for tablets,.as water-keeping laxatives and 7 [asfillers in pharmaceutical, rubber, plastic and chemof embodiments of thepre'sent invention; It should be 1111- de'rstood that these examples are not intended to limit the invention and that obvious changes may be made by those skilled in the .art without changing the essential characterzation, washing and drying, substantially as in Example 1, 540 g. of a product with a water'regain of 10 g./ g. of the dry product were obtained.

V a 100 g. ofldextran (M =1,800,-0O0)were dissolved in 2000 of an aqueous. 0.5 n'solu'tion of sodium hydroxide and 100 g. of epichlorohydrin were, addedthereto. The mixture was heated for 8 hours at 55 C. A gel was thereby formed, After grinding, neutralization, washing and drying, substantially as Example 1,60 g. of a prodnet with a water regain of 50 'g./g. of the dry product were obtained.

p n a V Exqnipl e-o 120 g. of dextran (M 5000) were dissolved in so ml. of an aqueous 5 n'solutionof sodium hydroxide and 24 g.

. of epichlorohydrin were added thereto. After 24 hours at room temperature the mass had solidified to a' gel which was cured by heating to 40 C. for 24 hours. After grinding, neutralization, washing and drying, substantially as in Example 1, -74 g. of a product with a water regain of 9 1 '1 kg. ofdextran. (M =40,000) were dissolved in 1 liter of an aqueous 4 11 solution of sodium hydroxide and 550 g. of 'epichlorohydrin were added thereto; The'temperature rapidly rose to C. and this temperature was maintained for 24 hours. After grinding, neutralization, wash ing and drying, substantially as in Example 1, 1.1 kg. of a thereto.. After 3 hours at room temperature a gel had product With a water regain cf-l.8 .g./ g. of the dry product were obtained. The product was fractionated into .two.-

fractions. The main fraction, 700 g., had a particle size ing, substantially as an Example 1, 28 g. of a product hav-.

ing a water regain of 3.5 g./ g. were obtained. The main fraction had a particle size within the range of about 0.3 to 2 mm.

ExamplaQ 100 g. .of.dextran (M =1,800,,O) were dissolvedtin 500 ml. of an aqueous 2 n solution of potassium hydroxide and 30 g. of glycerine-1,3-dichlorohydrin were added at room temperature. After 15 minutes a gel had been formed. After curing for 5 hours, the gel was treated substantially as in Example 1.

Example 60 g. of dextran (M =40,000) were dissolved in 140 ml. of water, whereupon 50 g. of solid calcium hydroxide and 25 g. of epichlorohydrin were added thereto. After 2 hours at room temperature a gel had been formed. It was cured by heating to 60 C. for 72 hours. After grinding, neutralizing, washing and drying, substantially as in Example 1, 68 g. of a product with a water regain of 3.9 g./ g. of the dry product were obtained.

Example 11 25 g. of sodiumcarboxymethyldextran (M -40,000) were dissolved in 25 ml. of an aqueous 2 n solution of sodium hydroxide and 5 g.- of epichlorohydrin were added thereto. After 1 hour at room temperature a gel had been formed. It was cured at 60 C. for 48 hours. The water regain of the product so obtained was 3.2 g./g. of the dry product.

Example 12 40 g. of Z-hydroxypropyldextran (M 40,000) were dissolved in 40' ml. of an aqueous 2 11 solution of NaOH, and 8 g. of epichlorohydrin were added thereto. The solution was left to stand at room temperature overnight and a 'gel was thereby formed. It was cured at 60 C. for 48 hours. The water regain of the product so obtained was 8 g./g. of the dry product.

- Example 1 Example 14 50 g. of dextranglycerineglycosid (M =80,000) were dissolved in 50 ml. of an aqueous 2 11 solution of sodium hydroxide and 10 g. of epichlorohydrin were added thereto. After 2 hours a gel had been formed, which was cured for 20 hours at 45 C. and then treated substantially as in Example 1.

I Example 200 g. of dextran (M -40,000) were dissolved in 200 ml. of an aqueous 4 11 solution of sodium hydroxide and 100 g. of l,4-butandiol-bis-epoxypropyl ether were added The mixture was heated for 24 been formed whichwas cured by heating to 60 C. for 24 hours. After grinding, neutralization, washing and drying similarly as in Example .l,.260 g.. of ,a product with a water regain of.1.9 g.; per g. of dryproduct were obtained.

Example 1 6 1 25 g pf dextran (M =40,000)-wer e dissolvedin 25 ml. of an aqueous 4 n solution;ofjsodiurn hydroxide; and 7.3. g. of l, 2,3,4 -diepoxybutan were added thereto. After ;10-

minutes; at roomtemperature a gel was formed. After the heat evolution had ceased, {the product was cured at 60? C. j

for, 24. hours. After-grinding; neutralization, washing and dryi similarly as -in Example 1, 27 g, ofa product with a water regain of 2.7 g./ g. of the.;-dry product were 1 ml. of an aqueous 2 nsolution of-sodium hydroxide and 15 got bisepoxypropyl ether were added thereto. The polymerisation was ,started at room temperature. After. 1 hour a gel had been formed which; was cured at 50. C

drying, similarly as. stated in Example 1, 63 g. of a product with the water regain 1.6 g./ g. of the dry product were obtained.

MISCELLANEOUS Those skilled in the chemical arts and particularly in the art to which this invention pertains will readily appreciate that many modifications of the basic invention set forth here are possible. For example, it is quite possible that other closely related compounds and reaction conditions might work as well as the herein specifically described compounds and reaction conditions, and there would certainly be no invention involved in trying such closely related compounds and reaction conditions in View of the present broad disclosure. All of these modifications are considered to be within the scope of the present claims by virtue of the well-established doctrine of equivalents.

What is claimed is:

1. As a product, a copolymerization product in gel grain form comprising a three-dimensional macroscopic network of dextran substances, built up of chains of mainly alpha-l,6-glucosidically bonded glucose residues, bonded together by ether bridges of the general type -ROX-OR, wherein R represents the dextran substances and X is an aliphatic radical containing from 3 to 10 carbon atoms, the said copolymerizationproduct being water-insolube but being capable of absorbing water with swelling, the water regain of the product being within the range of about 1 to 50 g./g. of the dry gel'product. I

2. As a product, suitable for separating solutes with difierent molecular sizes from a solution-by molecular sieving techniques, a copolymerization product in the form of gel grains having an average diameter within the range of about 0.01 to 2.0 mm. and consisting of a threedimensional macroscopic network of dextran substances, built up of chains of mainly alpha l,6-glucosidically bonded glucose residues, bonded together by ether bridges of the general type R-O--X-OR, wherein R represents the dextran substances and X is an aliphatic radical containing from 3 to 10 carbon atoms, the said gel grains being water-insoluble but capable of absorbfor 24 hours; After grinding, neutralizing, washing and .dextran substance, in the presence of an alkaline reacting" substance as catalyst, the said tbifunctional organicsub- 7 as catalyst, the said epoxy compound beingselected from propyl ether, ethyleneglycol-bis-epoxypropyl ether and l,4-'butan diol-bis-epoxypropyl ether, carrying out the reaction at a temperature between about 15 C. and about 90 C. and thereby forming a gel, subjecting said' gel to heat treatment at an elevated temperature not ex ceeding 90 Cl, and recovering the resultant gel product.

'4. The process of claim 3, wherein the catalyst consists of an alkali metal hydroxide. I t 7 5. The process'of claim 3 wherein the gel product is granulated down to an average particle size within the range 0.01 to 2.0 mm.

6. The process which comprises reacting an aqueous solution of '10 to 70% by weight of a hydroxyl groupcontaining deXtran substance with an aliphatic epoxy compound capable' of reacting with the hydroxyl groups of the' dextran substancevwith the formation of ether bridges the group consisting of epic hlorohydrin, dichlorohydrin, diepoxybutane, bis-epoxypropyl ether, ethyleneglycol-bisepoxypropyl ether and 1,4 butane-diol-bis-epoxypropyl ether, carrying out the reactionat a temperature between about 15 C. and about 90 C. and thereby forming a gel, completing the reaction by subjecting said gel to heat treatment at a temperature of from 30 to 90 C., granulat- V 7 ing the gel down to an average particle size within the 'ing the granulated product, and recoveringthe resultant gel grains. a 7. The process of claim 6, wherein the hydroxyl group- 1 20 between the dextran molecules, in the ratio of'at least I 10 molecules of the epoxy compound per molecule of it the dextran substance, in the presence of sodium hydroxide range .of about 0.01 to 2.0 mm, neutralizing and-washcontaining' dextran substance has an average molecular weight between aboutgSOOO and about 1,800,000.

8. The process of claim 6, Wherein the hydroxyl groupcontaining dextran substance has-an average molecular weight'of aboutAOyOOO. t t

References Cited in the'file of this patent V UNITED STATES PATENTS 2,671,799

Gaver et al., i Mar..9, 1954 

3. THE PROCESS, WHICH COMPRISES REACTING AN AQUEOUS SOLUTION OF 10 TO 70% BY WEIGHT OF A HYDROXYL GROUPCONTAINING DEXTRAN SUBSTANCE WITH A BIFUNCTIONAL ORGANIC SUBSTANCE CAPABLE OF REACTING WITH THE HYDROXYL GROUPS OF THE DEXTRAN SUBSTANCE, IN THE RATIO OF AT LEAST 10 MOLECULES OF THE BIFUNCTIONAL SUBSTANCE PER MOLECULE OF THE DEXTRAN SUBSTANCE, IN THE PRESENCE OF AN ALKALINE REACTING SUBSTANCE AS CATALYST, THE SAID BIFUNCTIONAL ORGANIC SUBTANCE BEING SELECTED FROM THE GROUP CONSISTING OF EPICHLOROHYDRIN, DICHLOROHYDRIN, DIEPOXYBUTANE, BIS-EPOXYPROPLY ETHER, ETHYLENEGLYCOL-BIS-EPOXYPROPYL ETHER AND 1,4-BUTANE-DIOL-BIS-EPOXYPROPYL ETHER, CARRYING OUT THE REACTION AT A TEMPERATURE BETWEEN ABOUT 15*C. AND ABOUT 90*C. AND THEREBY FORMING A GEL, SUBJECTING SAID GEL TO HEAT TREATMENT AT AN ELEVATED TEMPERATURE NOT EXCEEDING 90*C., AND RECOVERING THE RESULTANT GEL PRODUCT. 